Image Forming Device Having Feed Tray and Retaining Unit Retaining Photosensitive Drums

ABSTRACT

An image forming device includes: a main casing; a retaining unit; a feed tray; and a pickup roller. The retaining unit retains a plurality of photosensitive drums juxtaposedly arrayed and spaced away from each other in an array direction. The retaining unit is movable in the array direction between a mounted position in which the retaining unit is mounted in the main casing and a pulled-out position in which the retaining unit is pulled out of the main casing. The feed tray is configured to accommodate a first transferred medium. The pickup roller is configured to pick up the first transferred medium accommodated in the feed tray. The pickup roller is arranged to overlap with the retaining unit in the array direction.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/457,075, filed on Mar. 13, 2017, which is a continuation of U.S.patent application Ser. No. 14/933,883, filed on Nov. 5, 2015, U.S. Pat.No. 9,599,948 B2, issued Mar. 21, 2017, which is a continuation of U.S.patent application Ser. No. 14/203,055, filed on Mar. 10, 2014, now U.S.Pat. No. 9,182,738 B2, issued Nov. 10, 2015, which is a continuation ofU.S. patent application Ser. No. 13/361,385, filed on Jan. 30, 2012, nowU.S. Pat. No. 8,712,282 B2, issued Apr. 29, 2014, which claims priorityfrom Japanese Patent Application No. 2011-027517 filed Feb. 10, 2011.The contents of the above noted applications are incorporated herein byreference in their entirety.

TECHNICAL FIELD

The present invention relates to an image forming device using anelectrophotographic method.

BACKGROUND

One electrophotographic type color printer conventionally well known inthe art is an intermediate transfer type color printer. One suchintermediate transfer type color printer includes a plurality of processcartridges each having the photosensitive drum for one of four colors, adrawer for retaining the plurality of process cartridges, an endlessbelt that is disposed below the plurality of process cartridges andcontacts the photosensitive drum of each process cartridge, a secondarytransfer roller that contacts a rear portion of the endless belt, asheet supply tray that is disposed below the endless belt, and adischarge tray that is formed on the top of the printer.

In this color printer, each sheet of paper accommodated in the sheetsupply tray is conveyed upward from the sheet supply tray so as to passthrough a position between the endless belt and the secondary transferroller. Then, the sheet is discharged to the discharge tray so as to beconveyed frontward. In other words, the sheet accommodated in the sheetsupply tray passes through a generally C-shaped conveying path(so-called C-path) to be discharged to the discharge tray.

Further, this image forming device is capable of so-called “frontaccess”, replacing each process cartridge by pulling the drawerfrontward and setting the sheet of paper in the sheet supply tray bypulling the sheet supply tray frontward.

SUMMARY

With regard to the above-described color printer, proposal has been madethat a manual feed path accessible from a front side is provided.

If such a manual feed path is provided in the color printer, a space fordisposing a mechanism for the manual feed path is required at a positionbetween the endless belt and the sheet supply tray. This may increasethe size of the printer.

In view of the foregoing, it is an object of the present invention toprovide a compact image forming device having a second conveying pathaccessible from a pulled-out position side of a retaining unit.

In order to attain the above and other objects, the present inventionprovides an image forming device including: a main casing; a retainingunit; a feed tray; and a pickup roller. The retaining unit retains aplurality of photosensitive drums juxtaposedly arrayed and spaced awayfrom each other in an array direction. The retaining unit is movable inthe array direction between a mounted position in which the retainingunit is mounted in the main casing and a pulled-out position in whichthe retaining unit is pulled out of the main casing. The feed tray isconfigured to accommodate a first transferred medium. The pickup rolleris configured to pick up the first transferred medium accommodated inthe feed tray. The pickup roller is arranged to overlap with theretaining unit in the array direction.

According to another aspect of the present invention, the presentinvention provides an image forming device including: a main casing; aretaining unit; a transfer belt; a transfer roller; and a feed tray. Theretaining unit retains a plurality of photosensitive drums juxtaposedlyarrayed and spaced away from each other in an array direction. Theretaining unit is movable in the array direction between a mountedposition in which the retaining unit is mounted in the main casing and apulled-out position in which the retaining unit is pulled out of themain casing. The transfer belt is arranged in confrontation with theplurality of photosensitive drums to be transferred with developersupported on each photosensitive drum. The transfer belt has adownstream end portion in a mounting direction in which the retainingunit is moved from the pulled-out position to the mounted position. Thetransfer roller is disposed in confrontation with the downstream endportion to transfer the developer, which is transferred to the transferbelt, to a transferred medium. The feed tray includes a lift member anda plate. The lift member is configured to lift a first transferredmedium. The plate is disposed above the lift member and configured toplace thereon a second transferred medium which is different from thefirst transferred medium and which has been supplied into the maincasing.

BRIEF DESCRIPTION OF THE DRAWINGS

The particular features and advantages of the invention as well as otherobjects will become apparent from the following description taken inconnection with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a color printer as an image formingdevice according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of the color printer taken along theline A-A in FIG. 1;

FIG. 3 is an exploded cross-sectional view of a sheet supply tray of thecolor printer according to the first embodiment of the presentinvention;

FIG. 4 is an explanatory view illustrating an insertion/removal processfor a process cartridge of the color printer according to the firstembodiment of the present invention;

FIG. 5 is an explanatory view illustrating a paper jam process of asecond conveying path in the color printer according to the firstembodiment, in which the sheet supply tray has been pulled out;

FIG. 6 is an explanatory view illustrating a paper jam process of asecond conveying path in a color printer according to a secondembodiment of the present invention, in which a process unit has beenpulled out;

FIG. 7 is a side view of the process unit shown in FIG. 6; and

FIG. 8 is an explanatory view illustrating the paper jam process of thesecond conveying path in the color printer according to the secondembodiment, in which a sheet conveying member has been separated from aprocess frame.

DETAILED DESCRIPTION

An image forming device according to a first embodiment of the presentinvention will be described while referring to FIGS. 1 to 5 wherein likeparts and components are designated by the same reference numerals toavoid duplicating description.

1. Overall Structure of Color Printer

As shown in FIG. 1, the image forming device according to the firstembodiment is a horizontal intermediate transfer type color printer 1.

The color printer 1 is a multifunction device that is integrallyprovided with a main casing 2 and a flatbed scanner 3 for reading imagefrom original documents. The flatbed scanner 3 is disposed above themain casing 2.

Within the main casing 2, the color printer 1 is further provided with asheet supply unit 4 and an image forming unit 5. The sheet supply unit 4functions to supply a sheet of paper P to the image forming unit 5. Theimage forming unit 5 functions to form images on the sheet of paper Psupplied from the sheet supply unit 4.

(1) Main Casing

The main casing 2 has a box shape that is substantially rectangular in aside view. The sheet supply unit 4 and the image forming unit 5 aremounted in the main casing 2. The main casing 2 has one side wall inwhich an opening 6 is formed. A front cover 7 is provided on the sidewall so as to be pivotally movable about a lower end thereof between aclosed position for closing the opening 6 and an open position foropening the opening 6.

The terms “upward”, “downward”, “upper”, “lower”, “above”, “below”,“beneath”, “right”, “left”, “front”, “rear” and the like will be usedthroughout the description assuming that the color printer 1 is disposedin an orientation in which it is intended to be used. In the followingdescription, the side of the color printer 1 on which the front cover 7is provided (left side in FIG. 1) will be referred to as the front sideof the color printer 1, and a side opposite to the side (right side inFIG. 1) will be referred to as the rear side of the color printer 1. Thetop, bottom, left, and right sides of the color printer 1 in thefollowing description will be based on the reference point of a userviewing the color printer 1 from the front side.

(2) Sheet Supply Unit

The sheet supply unit 4 includes a sheet supply tray 8 for accommodatingsheets of paper P.

The sheet supply tray 8 is disposed at a bottom portion of the maincasing 2. The sheet supply tray 8 is detachably mounted in the maincasing 2. Further, the sheet supply tray 8 includes a lift member 9 forlifting a rear edge of the sheet P up and down.

The lift member 9 is formed in a generally rectangular plate shapeextending in a frontward/rearward direction. The lift member 9 isdisposed at a posterior half of a bottom surface of the sheet supplytray 8 and pivotally movable about a front edge thereof. Further, a rearedge of the lift member 9 is urged upward by an urging member (notshown) such as a coil spring.

The lift member 9 is in a slanted posture such that the lift member 9slants upward toward the rear edge by an urging force of the urgingmember (not shown). When the lift member 9 is in the slanted posture,the rear edge of the sheet P is lifted upward toward a pickup roller 10(described later) to be pinched between the lift member 9 and the pickuproller 10.

The sheet supply unit 4 includes the pickup roller 10, a sheet supplyroller 11, a sheet supply pad 12, a pair of pinch rollers 13, and a pairof registration rollers 14. The pickup roller 10 is disposed above arear end portion of the sheet supply tray 8, and opposite and above therear edge of the lift member 9. The sheet supply roller 11 is disposedrearward of the pickup roller 10. The sheet supply pad 12 is disposedbelow and opposite the sheet supply roller 11. The pair of pinch rollers13 opposes each other in a vertical direction. The pair of pinch rollers13 is disposed rearward of the sheet supply roller 11 and contact thesheet supply roller 11. The pair of registration rollers 14 opposes eachother in the frontward/rearward direction and disposed above the sheetsupply roller 11.

The sheets P (indicated by a solid line shown in FIG. 1) accommodated inthe sheet supply tray 8 are conveyed between the sheet supply roller 11and the sheet supply pad 12 in association with rotation of the pickuproller 10, and separated sheet by sheet in association with rotation ofthe sheet supply roller 11. Then, in association with rotation of thesheet supply roller 11, the separated sheet P is conveyed toward theregistration rollers 14 while passing between the sheet supply roller 11and each pinch roller 13. In association with rotation of theregistration rollers 14, the sheet P is conveyed to the image formingunit 5 (between an intermediate transfer belt 30 (described later) and asecondary transfer roller 27 (described later)) at a prescribed timing.This conveying path extending from the sheet supply tray 8 to the imageforming unit 5 through the sheet supply roller 11, the pinch rollers 13,and the registration rollers 14 corresponds to a first conveying path.

(3) Image Forming Unit

The image forming unit 5 is disposed above the sheet supply unit 4. Theimage forming unit 5 includes a process unit 15, a transfer unit 17, anda fixing unit 18.

(3-1) Process Unit

The process unit 15 is disposed above and opposite the sheet supply tray8 and also disposed frontward of the pickup roller 10 and the sheetsupply roller 11 so as to be overlapped with the pickup roller 10 andthe sheet supply roller 11 when projected in the frontward/rearwarddirection (a sliding direction or a juxtaposed direction). In otherwords, the process unit 15 is arranged to overlap with the pickup roller10 and the sheet supply roller 11 in the frontward/rearward direction.The process unit 15 retains four process cartridges 19 corresponding tofour colors (cyan, magenta, yellow, and black). Further, the processunit 15 is slidably movable in the frontward/rearward direction betweena mounted position in which the process unit 15 is mounted in the maincasing 2 and a pulled-out position in which the process unit 15 ispulled out of the main casing 2. That is, the process unit 15 isslidably mounted on the main casing 2 in the sliding direction.

Four process cartridges 19 are juxtaposedly arrayed with each other atregular intervals in the frontward/rearward direction. Morespecifically, a black process cartridge 19K, a yellow process cartridge19Y, a magenta process cartridge 19M, and a cyan process cartridge 19Care aligned in this order from front to rear.

Further, each process cartridge 19 includes a photosensitive drum 20, aScorotron charger 21, a developing unit 22, and an LED unit 16.

The photosensitive drum 20 is cylindrical in shape extending in arightward/leftward direction (longitudinal direction) and oriented withits axis along the rightward/leftward direction.

The Scorotron charger 21 is disposed diagonally below and rearward ofthe corresponding photosensitive drum 20, and confronts but does notcontact the corresponding photosensitive drum 20.

The developing unit 22 is disposed diagonally below and frontward of thecorresponding photosensitive drum 20. The four developing units 22 arejuxtaposedly arrayed with each other at regular intervals in thefrontward/rearward direction. The developing unit 22 includes adeveloping roller 23.

The developing roller 23 is rotatably supported in an upper end of thecorresponding developing unit 22. An upper rear edge of the developingroller 23 is exposed through an upper edge of the developing unit 22 andcontacts the corresponding photosensitive drum 20 from below.

The developing unit 22 also includes a supply roller 24 for supplyingtoner to the corresponding developing roller 23 and athickness-regulating blade 25 for regulating the thickness of the tonersupplied to the developing roller 23. Further, the developing unit 22includes a toner accommodating section 39 for accommodating toner asdeveloper for a corresponding color therein. The toner accommodatingsection 39 is disposed below the supply roller 24. The toneraccommodating section 39 is formed in a configuration such that twocylindrical bodies extending in the rightward/leftward direction areconnected to each other in the frontward/rearward direction.

The LED unit 16 is disposed rearward of the corresponding developingunit 22. Further, the LED unit 16 is disposed below the correspondingphotosensitive drum 20 and confronts the corresponding photosensitivedrum 20. The LED unit 16 exposes a surface of the correspondingphotosensitive drum 20 based on prescribed image data.

(3-2) Transfer Unit

The transfer unit 17 includes a belt unit 26 and the secondary transferroller 27.

The belt unit 26 is disposed above the process unit 15 so as to confronteach photosensitive drum 20 from above and oriented in thefrontward/rearward direction. In other words, the belt unit 26 opposesthe process unit 15 in the vertical direction.

The belt unit 26 includes a drive roller 28, a driven roller 29, theintermediate transfer belt 30, and four primary transfer rollers 31.

The drive roller 28 and the driven roller 29 are arranged inconfrontation with and spaced apart from each other in thefrontward/rearward direction.

The intermediate transfer belt 30 is stretched around the drive roller28 and the driven roller 29, with a lower portion of the intermediatetransfer belt 30 contacting each of the photosensitive drums 20. Theintermediate transfer belt 30 circulates so that the lower portion ofthe intermediate transfer belt 30 in contact with the photosensitivedrums 20 moves rearward.

Each primary transfer roller 31 is disposed in confrontation with thecorresponding photosensitive drum 20, interposing the lower portion ofthe intermediate transfer belt 30 between the primary transfer roller 31and the photosensitive drum 20.

The secondary transfer roller 27 is disposed rearward of the belt unit26. Further, the secondary transfer roller 27 is disposed inconfrontation with the drive roller 28 of the belt unit 26, interposingthe intermediate transfer belt 30 between the secondary transfer roller27 and the drive roller 28.

(3-3) Fixing Unit

The fixing unit 18 is disposed above the secondary transfer roller 27.The fixing unit 18 includes a heating roller 37 and a pressure roller 38disposed in confrontation with the heating roller 37.

(3-4) Image Forming Operations

(3-4-1) Developing Operation

The toner accommodated in the toner accommodating section 39 of thedeveloping unit 22 is supplied to the supply roller 24, and then to thedeveloping roller 23.

As the developing roller 23 rotates, the thickness-regulating blade 25regulates the toner carried on the surface of the developing roller 23to a prescribed thickness, so that the developing roller 23 carries auniform thin layer of toner thereon. The toner supplied to thedeveloping roller 23 is positively tribocharged between thethickness-regulating blade 25 and the developing roller 23.

In the meantime, the Scorotron charger 21 applies uniform charge ofpositive polarity to a surface of the corresponding photosensitive drum20 as the photosensitive drum 20 rotates. Subsequently, the LED unit 16exposes the surface of the corresponding photosensitive drum 20 based onimage data. An electrostatic latent image corresponding to an image tobe formed on the sheet P is formed on the surface of the photosensitivedrum 20.

As the photosensitive drum 20 continues to rotate, the positivelycharged toner carried on the surface of the developing roller 23 issupplied to the electrostatic latent image formed on the surface of thephotosensitive drum 20, thereby developing the electrostatic latentimage into a visible toner image through reverse development. Thus, thetoner image is formed on the surface of the photosensitive drum 20.

(3-4-2) Transfer and Fixing Operations

The toner image formed on the surface of each photosensitive drum 20through reverse development is primary-transferred onto the lowerportion of the intermediate transfer belt 30 conveyed rearward fromfront, thereby forming a color image on the intermediate transfer belt30.

The color image formed on the intermediate transfer belt 30 issecondary-transferred onto the sheet P supplied from the sheet supplyunit 4 while the intermediate transfer belt 30 passes through a positionN where the intermediate transfer belt 30 confronts the secondarytransfer roller 27.

The color image transferred onto the sheet P is thermally fixed to thesheet P by heat and pressure in the fixing unit 18, as the sheet Ppasses between the heating roller 37 and the pressure roller 38.

(4) Discharge

After the color image has been fixed to the sheet P in the fixing unit18, the sheet P is discharged by discharge rollers 32 onto a dischargetray 33 formed on a top surface of the main casing 2.

(5) Flatbed Scanner

The flatbed scanner 3 is disposed above the discharge tray 33. Theflatbed scanner 3 includes a restraining cover 34, a glass plate 35, anda CCD sensor 36. After an original document is placed between therestraining cover 34 and the glass plate 35, the CCD sensor 36 isslidingly moved to read image data from the original document.

Based on the image data read from the original document, an image isformed on the sheet P in the image forming unit 5 as described above.

2. Main Casing

The main casing 2 includes an outer casing 41 and an inner casing 42(FIG. 2). The outer casing 41 defines an outer shell of the colorprinter 1. The inner casing 42 is provided inside the outer casing 41.

(1) Details of Outer Casing

The outer casing 41 is formed in a generally box-shape. The outer casing41 has a front wall on which the front cover 7 is provided.

The front cover 7 has a lower end that is pivotally movably connected toa bottom wall of the outer casing 41. An opening 43 is formed in a lowerportion of the front cover 7. When the front cover 7 is in the closedposition, the sheet supply tray 8 is inserted into or removed from themain casing 2 through the opening 43.

Further, the front cover 7 includes a manual insertion guide 47. Themanual insertion guide 47 extends diagonally below and rearward from anupper edge of the opening 43 toward a position between a bottom wall ofthe process unit 15 and a sheet conveying member 61 (FIG. 2) of thesheet supply tray 8.

(2) Details of Inner Casing

As shown in FIGS. 1 and 2, the inner casing 42 is of a hollowrectangular cuboid configuration and elongated in the frontward/rearwarddirection. The inner casing 42 has a vertical length and a lateral(right to left) length such that the process unit 15, the belt unit 26,and the sheet supply tray 8 can be accommodated therein. The innercasing 42 is accommodated in the outer casing 41. The top, right, andleft walls of the inner casing 42 are spaced apart from those of theouter casing 41.

The inner casing 42 includes a belt accommodating section 44 in whichthe belt unit 26 is accommodated, a process unit supporting section 45for supporting the process unit 15, and a tray accommodating section 46in which the sheet supply tray 8 is accommodated.

(2-1) Belt Accommodating Section

The belt accommodating section 44 is disposed at an upper portion of theinner casing 42. The belt accommodating section 44 includes a pair ofright and left drum positioning members 48 for positioning eachphotosensitive drum 20 with respect to the belt unit 26.

Each of the pair of drum positioning members 48 is formed in a generallyplate shape extending in the frontward/rearward direction. The pair ofdrum positioning members 48 is arranged in confrontation with eachphotosensitive drum 20 at a position outside of a sheet contactingregion of each photosensitive drum 20 in the rightward/leftwarddirection. (Here, the sheet contacting region represents a region of thephotosensitive drum 20 that the sheet P contacts.) The pair of drumpositioning members 48 is also arranged spaced apart from each other inthe rightward/leftward direction, interposing the belt unit 26therebetween. An upper portion of each drum positioning member 48 isfixed to the top wall of the inner casing 42.

As shown in FIG. 4, each drum positioning member 48 has a lower portionin which four drum positioning recesses 49 corresponding to the fourphotosensitive drums 20 are formed.

Each drum positioning recess 49 is a substantially U-shaped notch openeddownward. More specifically, the drum positioning recess 49 is depressedupward from a lower edge of the drum positioning member 48. The fourdrum positioning recesses 49 are juxtaposedly arrayed with and spacedapart from each other in the frontward/rearward direction. Upperportions of right and left ends of the photosensitive drum 20 areretained in the drum positioning recesses 49 formed in the right andleft drum positioning members 48.

(2-2) Process Unit Supporting Section

As shown in FIG. 2, the process unit supporting section 45 is disposedimmediately below the belt accommodating section 44 at a substantiallyvertical center of the inner casing 42. The process unit supportingsection 45 has right and left side walls, each formed with a first guidegroove 52 and a second guide groove 54 (FIG. 4). The first guide groove52 serves to guide a rear portion of the process unit 15. The secondguide groove 54 serves to guide a front portion of the process unit 15.

The first guide groove 52 has a height (vertical length) allowing a pairof rear rollers 85 (described later) of the process unit 15 to beretained therein. The first guide groove 52 is formed in the processunit supporting section 45 across substantially the entire length in thefrontward/rearward direction and extends linearly in thefrontward/rearward direction. Further, the first guide groove 52 isformed such that a rear portion of the first guide groove 52 has aheight (vertical length) greater than a remaining portion thereof and aninterior space of the rear portion is expanded upward. A leaf spring 53(FIG. 4) is provided in the rear portion of the first guide groove 52 soas to curve in an arcuate shape with its convex side facing a topsurface of the first guide groove 52.

The leaf spring 53 is a curved metal plate extending in thefrontward/rearward direction. The leaf spring plate 53 has a front endfixed to a bottom surface of the first guide groove 52. Morespecifically, the leaf spring plate 53 extends diagonally above andrearward from the front end, then bends rearward and extends in thefrontward/rearward direction.

The second guide groove 54 is positioned below a front portion of thefirst guide groove 52. The second guide groove 54 has a height (verticallength) allowing a front roller 84 of the process unit 15 to be retainedtherein. The second guide groove 54 extends linearly in thefrontward/rearward direction. Further, the second guide groove 54 isformed such that a rear portion of the second guide groove 54 has aheight (vertical length) greater than a remaining portion thereof and aninterior space of the rear portion is expanded upward. A leaf spring 55(FIG. 4) is provided in the rear portion of the second guide groove 54so as to curve in an arcuate shape with its convex side facing a topsurface of the second guide recess 54.

The leaf spring 55 has a shape that is the same as the leaf spring plate53 provided in the first guide groove 52. The leaf spring plate 55 has afront end fixed to a bottom surface of the second guide groove 54.

(2-3) Tray Accommodating Section

The tray accommodating section 46 is disposed at a lower portion of theinner casing 42 and immediate below the process unit supporting section45.

3. Process Unit

(1) Process Frame

The process unit 15 includes a process frame 81 for integrally retainingthe process cartridges 19 and the LED units 16 therein.

The process frame 81 is formed in a substantially rectangular box shapewith an open top. The process frame 81 has right and left side wallseach formed with four cartridge guide recesses 82 (FIG. 2) and a bottomwall formed with five sets of three first roller retaining openings 83.Each of the four sets of the right and left cartridge guide recesses 82serve to guide removal of the process cartridge 19 from and insertion ofthe process cartridge 19 into the process unit 15. Each first rollerretaining opening 83 is adapted to retain a first roller member 73(described later) of a first conveying member 71 (described later).

Each cartridge guide recess 82 is formed on an inner surface of eachright and left side walls of the process frame 81 and extends in thevertical direction. Each of the right and left cartridge guide recesses82 is a depressed portion having a width capable of retaining a rotationshaft 92 (described later) of the photosensitive drum 20.

Each first roller retaining openings 83 is formed in a rectangular shapein a side view and penetrates the bottom wall of the process frame 81 inthe vertical direction. The three first roller retaining openings 83 ineach set are arrayed in the rightward/leftward direction at regularintervals one another. The five sets of the three first roller retainingopenings 83 are juxtaposedly arrayed with each other in thefrontward/rearward direction. More specifically, the foremost set of thethree first roller retaining openings 83 is disposed at the frontportion of the process unit 15, the rearmost set of the three firstroller retaining openings 83 is disposed at the rear portion of theprocess unit 15, and the remaining three sets of the three first rollerretaining openings 83 are respectively provided at positions betweeneach process cartridge 19. Each first roller retaining opening 83 has alength in the frontward/rearward direction greater than an outerdiameter of the first roller member 73 (described later) and a length inthe rightward/leftward direction greater than that of the first rollermember 73 (described later).

Each of the right and left side walls of the process frame 81 isprovided with the front roller 84 and the pair of rear rollers 85. Thefront roller 84 disposed at the right side wall is rotatably provided ina front portion of the right side wall and protrudes outward from theright side wall in the rightward/leftward direction. Likewise, the frontroller 84 disposed at the left side wall is rotatably provided in afront portion of the left side wall and protrudes outward from the leftside wall in the rightward/leftward direction. The pair of rear rollers85 disposed at the right side wall is rotatably provided in a rearportion of the right side wall and protrudes outward from the right sidewall in the rightward/leftward direction. Likewise, the pair of rearrollers 85 disposed at the left side wall is rotatably provided in arear portion of the left side wall and protrudes outward from the leftside wall in the rightward/leftward direction.

(2) Process Cartridge

Each process cartridge 19 has a pair of side plates 91 arranged inconfrontation with and spaced apart from each other in therightward/leftward direction. The photosensitive drum 20, the Scorotroncharger 21, and the developing unit 22 are disposed between the sideplates 91.

The rotation shaft 92 of the photosensitive drum 20 has right and leftends penetrating the right and left side plates 91 respectively androtatably supported to the side plates 91. Further, the right and leftends of the rotation shaft 92 protrude outward in the rightward/leftwarddirection from outer surfaces of the side plates 91.

The black process cartridge 19K integrally retains a belt cleaning unit93. The belt cleaning unit 93 is disposed frontward of the developingunit 22 of the black process cartridge 19K.

The belt cleaning unit 93 includes a waste toner retaining section 94, ascraping roller 96, a scraping blade 98, and a belt cleaning roller 95.

The waste toner retaining section 94 is formed in a generally box-shapehaving a top opening 97.

The scraping roller 96 is disposed above the opening 97 of the wastetoner retaining section 94. The scraping roller 96 is arranged inconfrontation with the opening 97.

The scraping blade 98 is formed in a generally plate shape extending inthe frontward/rearward direction. The scraping blade 98 has a front end(base end) that is fixed to the waste toner retaining section 94 at afront periphery of the opening 97 and a rear end (free end) thatcontacts the scraping roller 96 from below.

The belt cleaning roller 95 is rotatably supported to an upper portionof the belt cleaning unit 93 so as to contact the scraping roller 96from above.

The belt cleaning unit 93 is arranged such that the belt cleaning roller95 contacts the lower portion of the intermediate transfer belt 30 frombelow. The belt cleaning unit 93 serves to clean waste toner depositedon the surface of the intermediate transfer belt 30 by the belt cleaningroller 95. After the waste toner carried on the belt cleaning roller 95is supplied to the scraping roller 96, the waste toner carried on thescraping roller 96 is scraped off with the scraping blade 98. Hence, thewaste toner is retained in the waste toner retaining section 94.

(3) LED Unit

Each LED unit 16 includes an LED array supporting member 104 providedbetween the right and left side walls of the process frame 81 and an LEDarray 102 supported to the LED array supporting member 104.

The LED array supporting member 104 includes a support beam 106 and anLED array accommodating member 103.

The support beam 106 is formed in a generally quadrangular prism shapeextending in the rightward/leftward direction. The support beam 106 isdisposed between the right and left side walls of the process frame 81.

The LED array accommodating member 103 is formed in a generallyrectangular frame shape having a bottom wall and elongated in therightward/leftward direction. The bottom wall of the LED arrayaccommodating member 103 is connected to the support beam 106. The LEDarray accommodating member 103 has an internal dimension in thefrontward/rearward direction almost the same as (slightly greater than)an external dimension of the LED array 102 in the frontward/rearwarddirection. Further, the LED array accommodating member 103 has aninternal dimension in the rightward/leftward direction almost the sameas (slightly greater than) an external dimension of the LED array 102 inthe rightward/leftward direction.

The LED array 102 is formed in a generally quadrangular prism shape andelongated in the rightward/leftward direction. The LED array 102integrally holds a plurality of LEDs arrayed in the rightward/leftwarddirection therein. The LED array 102 has a length in therightward/leftward direction smaller than that of the photosensitivedrum 20 but greater than that of the sheet contacting region.

The LED array 102 has right and left ends, each having an LEDpositioning member 105 (FIG. 2) for positioning the LED array 102relative to the corresponding photosensitive drum 20.

Each LED positioning member 105 is formed in a plate shape that issubstantially rectangular in a side view. The LED positioning members105 are arranged to slightly protrude upward from the respective rightand left edges of the LED array 102. The LED positioning members 105contact the photosensitive drum 20 from below, thereby positioning theLED array 102 relative to the photosensitive drum 20 such that the LEDarray 102 is in confrontation with the photosensitive drum 20 at aninterval corresponding to the protruding length of the LED positioningmembers 105. It should be noted that the LED positioning member 105 isnot limited to the rectangular plate shape. For example, the LEDpositioning member 105 may be a generally disk shaped roller.

The LED array 102 is movable relative to the LED array accommodatingmember 103. The LED array 102 has a lower portion that is accommodatedin an upper portion of the LED array accommodating member 103. The LEDarray 102 is resiliently supported to the bottom wall of the LED arrayaccommodating member 103 by a pair of right and left compression springs108.

More specifically, the right compression spring 108 has one endconnected to a right end of the bottom wall of the LED arrayaccommodating member 103 and another end connected to a right end of theLED array 102. Likewise, the left compression spring 108 has one endconnected to a left end of the bottom wall of the LED arrayaccommodating member 103 and another end connected to a left end of theLED array 102. With this configuration, the LED array 102 is resilientlysupported relative to the bottom wall of the LED array accommodatingmember 103 via the compression springs 108.

(4) First Conveying Member

The process unit 15 includes five first conveying members 71. The fivefirst conveying members 71 are disposed at the bottom wall of theprocess frame 81. The five first conveying members 71 are juxtaposedlyarrayed with each other in the frontward/rearward direction. Morespecifically, the foremost first conveying member 71 is disposed at thefront portion of the process unit 15, the rearmost first conveyingmember 71 is disposed at the rear portion of the process unit 15, andthe remaining three of the first conveying members 71 are respectivelyprovided at positions between each process cartridge 19 in therightward/leftward direction (between each process cartridge 19 whenprojected in the vertical direction).

Each first conveying member 71 includes a first roller shaft 72 andthree first roller members 73. Each first roller member 73 is fixed tothe first roller shaft 72 and non-rotatable relative to the first rollershaft 72.

The first roller shaft 72 is formed in a generally columnar shape andelongated in the rightward/leftward direction. Further, the first rollershaft 72 has a length in the rightward/leftward direction greater thanthat of the process unit 15.

Each first roller member 73 has a hollow cylindrical configurationallowing the first roller shaft 72 to penetrate therethrough and iselongated in the rightward/leftward direction. The first roller member73 has an outer diameter greater than a thickness (i.e. a verticallength) of the bottom wall of the process frame 81 and an inner diameteralmost the same as an outer diameter of the first roller shaft 72.

Each first conveying member 71 is provided at the bottom wall of theprocess frame 81 such that each first roller member 73 is rotatablyretained in the corresponding first roller retaining opening 83 formedin the process frame 81 and the first roller shaft 72 is rotatablyembedded in the bottom wall of the process frame 81.

A drive force transmission mechanism (not shown) provided in the maincasing 2 inputs a drive force into each first conveying member 71.

4. Sheet Supply Tray

As shown in FIGS. 1 and 3, the sheet supply tray 8 is formed in asubstantially rectangular box shape with an open top. The sheet supplytray 8 is detachably accommodated in the tray accommodating section 46of the inner casing 42. The sheet supply tray 8 has a front wallarranged in confrontation with and spaced apart from the manualinsertion guide 47 of the front cover 7 in the vertical direction. Thefront wall of the sheet supply tray 8 has a vertical length smaller thanthat of the opening 43.

The front wall of the sheet supply tray 8 has an upper portion in whicha handle 57 is provided. The handle 57 is formed in a generally U-shapein cross-section having a bottom open.

The handle 57 extends forward from an upper edge of the front wall ofthe sheet supply tray 8, and then bends diagonally below and forward ata front edge of the extending portion of the handle 57. With thisconfiguration, the handle 57 has an upper surface extending in thefrontward/rearward direction.

A gap between the upper surface of the handle 57 and the manualinsertion guide 47 of the front cover 7 defines a manual insertionopening 75 into which a sheet P other than the sheet P accommodated inthe sheet supply tray 8 is inserted.

The sheet supply tray 8 includes a sheet conveying member 61 and a pairof right and left support members 62 (FIG. 2) for supporting the sheetconveying member 61.

The sheet conveying member 61 is formed in a generally plate shapeelongated in the frontward/rearward direction. The sheet conveyingmember 61 is detachable from or attachable to the pair of supportmembers 62. The sheet conveying member 61 has a length in therightward/leftward direction almost the same as an internal dimension ofthe sheet supply tray 8 in the rightward/leftward direction (FIG. 2).

The sheet conveying member 61 has a front portion sloping diagonallybelow and frontward. The front portion of the sheet conveying member 61confronts the upper portion of the front wall of the sheet supply tray 8from rear. The front portion of the sheet conveying member 61 has anupper surface serving as a front guide surface 76 extending diagonallyabove and rearward from front.

The sheet conveying member 61 has a rear portion formed in a generallywedge shape in a side view having an apex directed rearward. The rearportion of the sheet conveying member 61 is arranged in confrontationwith the rear edge of the lift member 9 from front. Further, the rearportion of the sheet conveying member 61 has an upper surface serving asa rear guide surface 77 extending diagonally below and rearward fromfront.

Further, the sheet conveying member 61 is formed with five sets of threesecond roller retaining openings 65. Further, the sheet conveying member61 includes two sets of a pair of right and left supported bosses 63supported by the pair of support members 62 and five second conveyingmembers 64 for conveying the sheet P.

Each second roller retaining opening 65 is formed in a square shape in aside view and penetrates the sheet conveying member 61 in the verticaldirection. When the process unit 15 and the sheet supply tray 8 ismounted in the main casing 2, each second roller retaining opening 65 isarranged so as to confront the corresponding first roller retainingopening 83 formed in the process frame 81 in the vertical direction.Each second roller retaining opening 65 has a length in thefrontward/rearward direction greater than an outer diameter of a secondroller member 67 (described later). Further, each second rollerretaining opening 65 has a length in the rightward/leftward directiongreater than that of the second roller member 67 (described later).

The sheet conveying member 61 has right and left side surfaces on whichthe right and left supported bosses 63 are respectively provided. Eachright supported boss 63 is formed in a generally cylindrical shapeprotruding outward from the right side surface of the sheet conveyingmember 61 in the rightward/leftward direction. One of the rightsupported bosses 63 is disposed at the front portion of the sheetconveying member 61 and a remaining one of the right supported bosses 63is disposed at the rear portion of the sheet conveying member 61.Likewise, each left supported boss 63 is formed in a generallycylindrical shape protruding outward from the left side surface of thesheet conveying member 61 in the rightward/leftward direction. One ofthe left supported bosses 63 is disposed at the front portion of thesheet conveying member 61 and a remaining one of the left supportedbosses 63 is disposed at the rear portion of the sheet conveying member61.

Each second conveying member 64 includes a second roller shaft 66 andthree second roller members 67. Each second roller member 67 is fixed tothe second roller shaft 66 and non-rotatable relative to the secondroller shaft 66.

The second roller shaft 66 is formed in a generally columnar shape andelongated in the rightward/leftward direction. Further, the secondroller shaft 66 has a length in the rightward/leftward direction almostthe same as that of the sheet conveying member 61.

Each second roller member 67 has a hollow cylindrical configurationallowing the second roller shaft 66 to penetrate therethrough and iselongated in the rightward/leftward direction. The second roller member67 has an outer diameter greater than a thickness (i.e. vertical length)of the sheet conveying member 61 and an inner diameter almost the sameas an outer diameter of the second roller shaft 66. Further, the secondroller member 67 has a length in the rightward/leftward directionsmaller than that of the first roller member 73.

Each second conveying member 64 is provided in the sheet conveyingmember 61 such that each second roller member 67 is rotatably retainedin the corresponding second roller retaining opening 65 formed in thesheet conveying member 61 and the second roller shaft 66 is rotatablyembedded in the sheet conveying member 61.

Each of the right and left support members 62 is formed in a generallyplate shape and elongated in the frontward/rearward direction. The rightsupport member 62 has front and rear portions, each formed with asupport recess (right support recess) 68 for receiving the rightsupported boss 63 of the sheet conveying member 61. Further, the rightsupport member 62 has a lower portion provided with three insertionbosses (right insertion bosses) 69. Likewise, the left support member 62has front and rear portions, each formed with a support recess (leftsupport recess) 68 for receiving the left support boss 63 of the sheetconveying member 61. Further, the left support member 62 has a lowerportion provided with three insertion bosses (left insertion bosses) 69.

Each right support recess 68 is a generally U-shaped recess formed in aninner surface of the right support member 62 and depressed downward froman upper edge of the right support member 62. Likewise, each leftsupport recess 68 is a generally U-shaped recess formed in an innersurface of the left support member 62 and depressed downward from anupper edge of the left support member 62.

The three right insertion bosses 69 are respectively disposed at front,center, and rear portions of the right support member 62 in thefrontward/rearward direction. Each right insertion boss 69 is formed ina generally cylindrical shape protruding outward (rightward) from anouter surface of the right support member 62 in the rightward/leftwarddirection.

Likewise, the three left insertion bosses 69 are respectively disposedat front, center, and rear portions of the left support member 62 in thefrontward/rearward direction. Each left insertion boss 69 is formed in agenerally cylindrical shape protruding outward (leftward) from an outersurface of the left support member 62 in the rightward/leftwarddirection.

Further, the sheet supply tray 8 has a pair of right and left sidewalls, each formed with three spring accommodating portions 59 and threeinsertion holes 60 at positions corresponding to the three insertionbosses 69 of the respective right and left support members 62.

Each spring accommodating portion 59 is formed in an inner surface ofeach right and left side wall of the sheet supply tray 8. The springaccommodating portion 59 has a rectangular shape in a side view and iselongated in the vertical direction.

A compression spring 58 is accommodated in each spring accommodatingportion 59. The compression spring 58 has one end connected to theinsertion boss 69 and another end connected to a bottom wall of thespring accommodating portion 59.

Each insertion hole 60 is a hole elongated in the vertical direction.Each insertion hole 60 (right insertion hole 60) formed on the right andleft side walls of the sheet supply tray 8 is formed so as to cutout theinner surface of the right and left side walls of the sheet supply tray8 toward an outer surface thereof and positioned at a positionoverlapped with an upper portion of the corresponding springaccommodating portion 59 when projected in the rightward/leftwarddirection. In other words, each insertion hole 60 is formed to overlapwith the upper portion of the spring accommodating portion 59 in therightward/leftward direction. Further, each insertion hole 60 has alength in the frontward/rearward direction greater than a diameter ofthe insertion boss 69.

The right support member 62 is resiliently supported to the bottom wallsof the three right spring accommodating portions 59 via the three rightcompression springs 58 by inserting the three right insertion bosses 69into the corresponding right insertion holes 60. Likewise, the leftsupport member 62 is resiliently supported to the bottom walls of theleft spring accommodating sections 59 via the three left compressionsprings 58 by inserting the three left insertion bosses 69 into thecorresponding left insertion holes 60. Hence, the pair of right and leftsupport members 62 is resiliently supported to the sheet supply tray 8.

The sheet conveying member 61 is supported to the support members 62, byengaging the supported bosses 63 with the corresponding support recesses68 formed in the support members 62. Hence, the sheet conveying member61 is supported to the pair of right and left support members 62.

With this configuration, the sheet conveying member 61 is constantlyurged upward by the urging force of the compression springs 58. Further,the sheet conveying member 61 is disposed below the process frame 81 andconfronts the process frame 81 such that each second roller member 67 isin pressure contact with the corresponding first roller member 73 frombelow. A top surface of the sheet conveying member 61 is arranged inconfrontation with and spaced apart from a bottom surface of the processframe 81.

When the sheet conveying member 61 is pressed downward, the sheetconveying member 61 moves downward against the urging force of thecompression springs 58.

5. Second Conveying Path

Conveyance of the sheet P in a second conveying path will be describedwhile referring to FIG. 1. The second conveying path corresponds to aconveying path extending from the manual insertion opening 75 to aposition between the pickup roller 10 and the lift member 9 through thefirst conveying members 71 and the second conveying members 64.

The sheet P inserted into the manual insertion opening 75 (indicated bya broken-line shown in FIG. 1) is guided to a nip region defined betweenthe foremost first conveying member 71 and the foremost second conveyingmember 64 (FIG. 4) by the manual insertion guide 47 of the front cover7, the upper surface of the handle 57 of the sheet supply tray 8, andthe front guide surface 76 of the sheet conveying member 61.

Then, the sheet P is conveyed rearward between the bottom surface of theprocess frame 81 and the top surface of the sheet conveying member 61while each first conveying member 71 is driven to rotate and each secondconveying member 64 follows rotation of the corresponding firstconveying member 71.

Subsequently, the sheet P is guided to the position between the pickuproller 10 and the lift member 9 by the rear guide surface 77 disposed inthe rear portion of the sheet conveying member 61.

That is, in the second conveying path, the sheet P inserted into themanual insertion opening 75 is conveyed to the position between thepickup roller 10 and the lift member 9, the position being locatedupstream of the position N in a sheet conveying direction of the firstconveying path.

In other words, the second conveying path joins the first conveying pathat the position between the pickup roller 10 and the lift member 9 thatis positioned upstream of the position N in the sheet conveyingdirection.

The sheet P conveyed to the first conveying path from the secondconveying path at the position between the pickup roller 10 and the liftmember 9 is conveyed to a position between the sheet supply roller 11and the sheet supply pad 12 by rotation of the pickup roller 10, asdescribed above. Then, the sheet P is conveyed upward toward theregistration rollers 14 so as to sequentially pass between the sheetsupply roller 11 and each pinch roller 13 by rotation of the sheetsupply roller 11. The sheet P is further conveyed to the position N at aprescribed timing by rotation of the registration rollers 14.

In other words, the first conveying path and the second conveying pathshare the pickup roller 10.

6. Removal and Mounting of Process Cartridge Relative to Main Casing

To remove the process cartridge 19 from the main casing 2 or to mountthe process cartridge 19 in the main casing 2, as shown in FIG. 4,initially, the front cover 7 is moved to the open position from theclosed position to open the opening 6. Next, the process unit 15 ispulled frontward from the main casing 2 through the opening 6.

Then, each rearmost roller 85 of the process unit 15 is separated fromthe corresponding leaf spring 53 at the rear portion of thecorresponding first guide recess 52. Each front roller 84 of the processunit 15 is also separated from the corresponding leaf spring 55 at therear portion of the corresponding second guide recess 54. Uponseparation of the rollers 54 and 85 from the leaf springs 53 and 55, theprocess unit 15 is moved downward so that each photosensitive drum 20 isseparated from the lower portion of the intermediate transfer belt 30.

At this time, the sheet conveying member 61 of the sheet supply tray 8is moved downward in association with the downward movement of theprocess unit 15.

When the process unit 15 is further pulled frontward, the process unit15 is guided by the first guide recesses 52 and the second guiderecesses 54 while maintaining a slight space between the lower portionof the intermediate transfer belt 30 and the process unit 15. Theprocess unit 15 is then pulled outward from the main casing 2.

Subsequently, the process cartridge 19 is removed from the pulled-outprocess unit 15. More specifically, to remove the process cartridge 19mounted in the process unit 15 from the process unit 15, the processcartridge 19 is pulled upward. To mount the process cartridge 19 in theprocess unit 15, the process cartridge 19 is positioned above theprocess frame 81 so that the right and left ends of the rotation shaft92 of the photosensitive drum 20 are respectively disposed above theright and left cartridge guide recesses 82. Then, the process cartridge19 is inserted into the process frame 81 from above.

By performing, in reverse order, the above-described operation forremoving the process unit 15 from the main casing 2, the process unit 15is mounted in the main casing 2.

More specifically, the process unit 15 is inserted into the main casing2 along the first guide recesses 52 and the second guide recesses 54.

At this time, the sheet conveying member 61 of the sheet supply tray 8is pressed downward by the process unit 15 to be moved downward againstthe urging force of the compression springs 58. Further, the processunit 15 is guided by the first guide recesses 52 and the second guiderecesses 54 to be inserted into the main casing 2, while maintaining aslight space between the lower portion of the intermediate transfer belt30 and the process unit 15.

Then, each rearmost roller 85 of the process unit 15 ride up over thecorresponding leaf spring 53 at the rear portion of the correspondingfirst guide recess 52. Each front roller 84 of the process unit 15 alsorides up over the corresponding leaf spring 55 at the rear portion ofthe corresponding second guide recess 54. The process unit 15 is thusmoved upward so that each photosensitive drum 20 is brought into contactwith the lower portion of the intermediate transfer belt 30.

As a result, the process unit 15 is mounted in the main casing 2 so asto be constantly biased upward by the biasing forces of the leaf spring53 and the leaf spring 55.

7. Paper Jam Fixing Process in Second Conveying Path

When paper jam occurs while the sheet P is conveyed in the secondconveying path, as shown in FIG. 5, the sheet supply tray 8 is pulledfrontward so as to be removed from the main casing 2.

The jammed sheet P is pulled outward from the main casing 2 togetherwith the pulled-out sheet supply tray 8 so as to be placed on the sheetconveying member 61. Alternatively, the jammed sheet P falls into thespace defined below the process unit 15 by removing the sheet supplytray 8 from the main casing 2.

Then, the sheet P placed on the sheet conveying member 61 or the sheet Pdropped into the space below the process unit 15 is collected to beremoved.

As described above, the sheet P jammed in the second conveying path canbe removed.

8. Operations and Effects

(1) In the color printer 1 according to the first embodiment of thepresent invention, as shown in FIG. 1, the second conveying path isconfigured such that the sheet P inserted into the manual insertionopening 75 is convey to the first conveying path at the position betweenthe pickup roller 10 and the lift member 9, the position being locatedupstream of the position N where the intermediate transfer belt 30confronts the secondary transfer roller 27 in the sheet conveyingdirection of the first conveying path. Further, the process unit 15 isprovided with the first conveying members 71 for conveying the sheet Pfed through the manual insertion opening 75.

Accordingly, the second conveying path can be defined in combinationwith the process unit 15. Compared with a case where a second conveyingpath is formed independently of the process unit 15, the color printer 1can be made more compact.

Consequently, the color printer 1 can be prevented from increasing insize, while the color printer 1 includes the second conveying pathcapable of accessible from the side where a user accesses to replace theprocess cartridge 19 or to supply the sheet P (i.e. front side).

Further, in the color printer 1 according to the first embodiment, theuser can access the second conveying path from the side where thereplacement of the process cartridge 19 and supply of the sheet P areperformed (i.e. front side). Even if a space around the color printer 1,such as a space at a rear, left or right side of the color printer 1, isrestricted, the user can easily access the second conveying path.

(2) Further, in the color printer 1 according to the first embodiment,as shown in FIGS. 1 and 3, the sheet supply tray 8 is provided with thesecond conveying members 64 that are arranged in confrontation with thecorresponding first conveying members 71 and configured to convey thesheet P fed through the manual insertion opening 75 in conjunction withthe first conveying members 71.

Hence, the sheet supply tray 8 and the process unit 15 can define thesecond conveying path therebetween. Accordingly, compared with a casewhere a second conveying path is formed independently of the sheetsupply tray 8 or the process unit 15, the color printer 1 can be mademore compact.

Further, removal of the sheet supply tray 8 from the main casing 2allows the second conveying path to open in the vertical direction.Hence, the sheet P jammed in the second conveying path can be easilyremoved therefrom.

More specifically, the sheet P jammed in the second conveying path canbe pulled outward from the main casing 2 together with the sheet supplytray 8. Alternatively, the sheet P jammed in the second conveying pathcan be dropped into the space defined below the process unit 15 byremoving the sheet supply tray 8 from the main casing 2.

Further, the sheet P placed on the sheet conveying member 61 or thesheet P dropped into the space below the process unit 15 can be easilycollected and removed.

(3) Further, in the color printer 1 according to the first embodiment,as shown in FIGS. 1 and 3, the second conveying members 64 areconstantly biased upward by the compression springs 58. The secondconveying members 64 are movable downward against the compressionsprings 58.

Hence, downward movement of the process unit 15 is permitted while thesecond conveying members 64 are in pressure contact with the firstconveying members 71 from below. When the process unit 15 is removedfrom or mounted in the main casing 2, the process unit 15 is slidablymovable while maintaining a gap between the process unit 15 and theintermediate transfer belt 30.

As a result, the process unit 15 can be smoothly removed from or mountedin the main casing 2, avoiding sliding contact between thephotosensitive drums 20 and the intermediate transfer belt 30.

(4) Further, in the color printer 1 according to the first embodiment,as shown in FIG. 1, when the process unit 15 is in the mounted position,the pickup roller 10 is provided at a position overlapped with theprocess unit 15 when projected in the frontward/rearward direction. Inother words, the pickup roller 10 is arranged to overlap with theprocess unit 15 in the frontward/rearward direction.

More specifically, the pickup roller 10 is disposed above the sheetsupply tray 8 and also disposed rearward of the process unit 15. Hence,the process unit 15 and the sheet supply tray 8 are arranged to be closeto each other in the vertical direction. Accordingly, the color printer1 can be made flatter, that is, can be downsized in the verticaldirection.

(5) Further, in the color printer 1 according to the first embodiment,as shown in FIG. 1, the first conveying path and the second conveyingpath share the pickup roller 10. Hence, it is not necessary to providetwo pickup rollers 10 for the first conveying path and the secondconveying path. Accordingly, the number of parts and components of thecolor printer 1 can be reduced.

(6) Further, in the color printer 1 according to the first embodiment,as shown in FIG. 1, each of the intermediate three first conveyingmembers 71 is disposed between each process cartridge 19 (i.e. eachphotosensitive drum 20).

Hence, the intermediate three first conveying member 71 can beefficiently allocated by utilizing each space defined between eachprocess cartridge 19. As a result, the color printer 1 can be made morecompact.

(7) Further, in the color printer 1 according to the first embodiment,as shown in FIG. 1, the process unit 15 includes the LED units 16 forexposing the corresponding photosensitive drums 20.

Hence, compared with a case where a member for exposing thephotosensitive drum 20 is provided independently of the process unit 15,the color printer 1 can be made more compact.

(8) Further, in the color printer 1 according to the first embodiment,as shown in FIG. 1, the process unit 15 includes a belt cleaning unit 93disposed in contact with the intermediate transfer belt 30 and adaptedto clean the intermediate transfer belt 30.

Hence, compared with a case where a member for cleaning the intermediatetransfer belt 30 is provided independently of the process unit 15, thecolor printer 1 can be made more compact.

9. Second Embodiment

A color printer 101 as an image forming device according to a secondembodiment of the present invention will be described while referring toFIGS. 6 to 8. In the following description, only parts differing fromthose of the above-described embodiment will be described.

In the above described first embodiment, the sheet conveying member 61is provided in the sheet supply tray 8. However, in the secondembodiment, as shown in FIG. 6, a sheet conveying member 161 is providedat a bottom section of a process unit 115. Note that parts andcomponents appearing in the second embodiment and the same as those inthe first embodiment will be designated by the same reference numeralsas those in the first embodiment to avoid duplicating description.

As shown in FIG. 7, the process unit 115 includes a process frame 181retaining each process cartridge 19 and the sheet conveying member 161.

The sheet conveying member 161 has right and left side surfaces whosefront and rear portions are connected to the process frame 181 byconnection arms 111. That is, the front and rear portions of the rightside surface of the sheet conveying member 161 are connected to a rightside wall of the process frame 181 by the two right connection arms 111,and the front and rear portions of the left side surface of the sheetconveying member 161 are connected to a left side wall of the processframe 181 by the two left connection arms 111.

Each connection arm 111 is formed in a generally lever-shape, having oneend pivotally movably supported to a lower portion of the correspondingside wall of the process frame 181 and another end pivotally movablysupported to the side surface of the sheet conveying member 161.

Further, each connection arm 111 is constantly biased in acounterclockwise direction in FIG. 7 by a coil spring 113 wound around apivot shaft 112 provided at the one end of the connection arm 111. Thecoil spring 113 has one end fixed to the side wall of the process frame181 and another end fixed to the right connection arm 111. That is, eachconnection arm 11 is urged by the coil spring 113 such that another endof the connection arm 11 comes close to the process frame 81.

With this configuration, the sheet conveying member 61 is biased in thecounterclockwise direction in FIG. 7 by the connection arms 111.Further, the sheet conveying member 61 is movable between a sheetconveying position (FIG. 7) and a jam processing position (FIG. 8). Whenthe sheet conveying member 61 is positioned at the sheet conveyingposition (FIG. 7), the sheet conveying member 61 is disposed below theprocess frame 81 and confronts the process frame 81 such that eachsecond roller member 67 is in pressure contact with the correspondingfirst roller member 73 from below. At this time, each connection arm 111extends diagonally below and rearward from the one end.

Further, the sheet conveying member 161 is positioned at the jamprocessing position, the sheet conveying member 161 is disposed belowand spaced apart from the process frame 81 by being pulled diagonallybelow and forward against the biasing force of the connection arms 111.At this time, each connection arm 111 extends downward.

In the second embodiment, when the sheet P is jammed in the secondconveying path, the process unit 115 is initially pulled frontward fromthe main casing 2 as shown in FIG. 6.

Then, as shown in FIG. 8, the sheet conveying member 161 is pulleddiagonally below and frontward to separate the sheet conveying member161 from the process frame 181. Then, the sheet P jammed between thesheet conveying member 161 and the process frame 181 is collected to beremoved.

As described above, the sheet P jammed in the second conveying path canbe removed.

In the color printer 101 according to the second embodiment, as shown inFIG. 8, the process unit 115 is provided with the second conveyingmembers 64 capable of separating (moving downward) from thecorresponding first conveying members 71.

Accordingly, the second conveying path can be formed in the process unit115. Hence, compared with a case where a second conveying path is formedindependently of the process unit 115, the color printer 101 can be mademore compact.

Further, the sheet P jammed in the second conveying path can be easilyremoved, by removing the process unit 115 from the main casing 2 to movethe second conveying members 64 downward for separating from thecorresponding first conveying members 71.

Further, in the color printer 101 according to the second embodiment,the same operations and effects of the first embodiment can be obtained.While the present invention has been described in detail with referenceto the present embodiments thereof, it would be apparent to thoseskilled in the art that various changes and modifications may be madetherein without departing from the spirit of the present invention.

What is claimed is:
 1. An image forming apparatus comprising: a maincasing; a sheet supply tray movable in a moving direction from an outerposition in which the sheet supply tray is outside the main casing to aninner position in which the sheet supply tray is inside the main casing;a belt unit including a first roller, a second roller, and anintermediate transfer belt stretched around the first roller and thesecond roller; a plurality of photosensitive drums mounted in the maincasing so as to be aligned in the moving direction, the plurality ofphotosensitive drums being aligned along the intermediate transfer belt;a transfer roller disposed such that the intermediate transfer belt isinterposed between the first roller and the transfer roller, the firstroller being disposed between the second roller and the transfer rollerin the moving direction; a pickup roller configured to feed a sheet fromthe sheet supply tray to the transfer roller; a first conveying rollerconfigured to convey a sheet to the transfer roller in the movingdirection; and a tray disposed between the intermediate transfer beltand the sheet supply tray in a vertical direction, the tray beingmovable in a direction the same as the moving direction from an outerposition in which the tray is outside the main casing to an innerposition in which the tray is inside the main casing, the tray includinga second conveying roller, the first conveying roller being configuredto convey a sheet with the second conveying roller toward the transferroller, and the first conveying roller being positioned inside the maincasing when the tray is located at the outer position.
 2. The imageforming apparatus according to claim 1, further comprising: a pluralityof LED units, each LED unit being configured to expose a correspondingphotosensitive drum to light and disposed between the correspondingphotosensitive drum and the sheet supply tray in the vertical direction.3. The image forming apparatus according to claim 2, wherein each LEDunit includes an LED array supporting part and an LED array supported bythe LED array supporting part, wherein the LED array supporting partincludes a support beam, and wherein the support beam is in aquadrangular prism shape extending in a direction parallel to an axialdirection of the photosensitive drum.
 4. The image forming apparatusaccording to claim 3, wherein the LED array supporting part of each LEDunit further includes an LED array accommodating part, in which thecorresponding LED array is accommodated, and wherein the LED arrayaccommodating part has an internal dimension greater than an externaldimension of the corresponding LED array.
 5. The image forming apparatusaccording to claim 3, wherein the LED array of each LED unit has alength in a direction parallel to an axial direction of thecorresponding photosensitive drum that is smaller than a length of thecorresponding photosensitive drum in the axial direction of thecorresponding photosensitive drum.
 6. The image forming apparatusaccording to claim 3, wherein the LED array of each LED unit is providedwith an LED positioning member configured to contact the correspondingphotosensitive drum from below, thereby positioning the LED arrayrelative to the corresponding photosensitive drum.
 7. The image formingapparatus according to claim 1, further comprising a retaining unitretaining the photosensitive drums, the retaining unit movable between amounted position, in which the retaining unit is mounted in the maincasing, and a pulled-out position, in which the retaining unit is pulledout of the main casing, in a direction parallel to the moving direction.8. The image forming apparatus according to claim 1, wherein the tray isconfigured to move together with the sheet supply tray.
 9. The imageforming apparatus according to claim 2, wherein the tray is disposed ata vertical position between the LED units and the sheet supply tray inthe vertical direction.
 10. The image forming apparatus according toclaim 2, wherein the first conveying roller is disposed at a verticalposition between the LED units and the sheet supply tray in the verticaldirection.
 11. The image forming apparatus according to claim 2, whereinthe second conveying roller is disposed between the LED units and thesheet supply tray in the vertical direction.
 12. The image formingapparatus according to claim 2, wherein the intermediate transfer beltis disposed confronting the photosensitive drums from above andcontacting the photosensitive drums.
 13. The image forming apparatusaccording to claim 1, further comprising: a plurality of other transferrollers disposed such that the intermediate transfer belt is interposedbetween the other transfer rollers and the photosensitive drums.
 14. Theimage forming apparatus according to claim 1, further comprising: athird conveying roller configured to convey the sheet from the firstconveying roller to the transfer roller, the third conveying rollerbeing disposed downstream from the first conveying roller in a directionthe same as the moving direction, wherein the tray includes a fourthconveying roller, the third conveying roller being configured to conveythe sheet with the fourth conveying roller toward the transfer roller,and the third conveying roller being positioned inside the main casingwhen the tray is located at the outer position.
 15. The image formingapparatus according to claim 14, wherein the second conveying roller andthe fourth conveying roller are arranged such that when the tray is atthe inner position, the second conveying roller is located below thefirst conveying roller and the fourth conveying roller is located belowthe third conveying roller.
 16. An image forming apparatus comprising: amain casing; a sheet supply tray configured to feed a sheet and movablein a moving direction from an outer position in which the sheet supplytray is outside the main casing to an inner position in which the sheetsupply tray is inside the main casing; a plurality of photosensitivedrums; a belt unit including a first roller, a second roller, and anintermediate transfer belt stretched around the first roller and thesecond roller; a transfer roller disposed such that the intermediatetransfer belt is interposed between the first roller and the transferroller; a first conveying roller configured to convey a sheet to thetransfer roller; and a tray disposed between the intermediate transferbelt and the sheet supply tray in a vertical direction, the tray beingmovable in a direction the same as the moving direction from an outerposition in which the tray is outside the main casing to an innerposition in which the tray is inside the main casing, the tray includinga second conveying roller, the first conveying roller being configuredto convey a sheet with the second conveying roller toward the transferroller, and the first conveying roller being positioned inside the maincasing when the tray is located at the outer position.
 17. An imageforming apparatus comprising: a main casing having an opening formed atone side of the main casing in a predetermined direction; a plurality ofphotosensitive drums mounted in the main casing so as to be aligned inthe predetermined direction; an intermediate transfer belt arranged toface the plurality of the photosensitive drums; a first roller arrangedat a lower position relative to the intermediate transfer belt, thefirst roller being configured to convey a sheet in the predetermineddirection from the one side of the main casing toward another side ofthe main casing, the other side of the main casing being opposite to theone side of the main casing in the predetermined direction; and a trayinstalled in the main casing so as to be removable from the one side ofthe main casing through the opening, the tray being configured tosupport a second roller, the first roller being disposed above thesecond roller when the tray is installed in the main casing.
 18. Theimage forming apparatus according to claim 17, wherein the first rolleris a driven roller.